Have you ever been watching a movie and one of the characters is suddenly unable to breathe, their chest feels tight, and they are clutching their left arm? What instantly comes to your mind? Likely, a myocardial infarction, otherwise known as a heart attack. Why does a heart attack cause left arm pain? This is due to a phenomenon called referred pain. There are two primary explanations for referred pain: 1) the nerve cells of organs follow similar pathways as certain musculoskeletal body regions and can be misinterpreted by the brain and 2) during development in the womb these areas originate out of the same embryonic tissue.
Referral patterns can also arise from non-visceral tissue (aka non-organs). For example, I have included some pictures of facet joint referral, where a joint in your spine can result in symptoms at a distant site. Many of us have been treated by a rehab professional who discerns that our knee pain is actually due to weakness in the hips or the cramping on the bottom of our feet is due to fascial restrictions in our low back. There are countless examples of how pain that may be felt so strongly in one area is not due to a pathological cause at that location.
But, what if I told you that you have no pain receptors? It’s true. We instead have something called nociception, which is the possibility of danger. With my patients I like to use an example of a rolled ankle (see stick figure drawings below). Previously, the medical community believed that tissues, such as ligaments, muscles, and tendons, in our ankle would send a message up to our brain “Ow! We are in pain!”. Within the last decade, the latest researchers in pain neuroscience have discovered the process works something more like this:
- Nociceptors in the tissues in your ankle tell you brain “Hey, man. We might be in danger here. We’ve rolled the ankle”
- Your brain then does some gnarly stuff where it processes this information and ponders “Has this happened before? Have I seen this happen to others? What do I know about rolled ankles?”
- After combining your past experiences with similar injuries and considering the context you are currently in (your physical environment, emotional/hormonal environment, stress level, etc) your brain will decide whether or not it is worth it to put out a pain signal
With most acute injuries, your brain will trigger a cascade of events that result in a pain response because your tissue is likely damaged and you need to protect it. But here is the interesting thing: tissues heal. Even if you do nothing to them, within 3-6 months they heal. Shy of a spinal cord injury, severe vision/hearing loss, or nerve cell death due to something like a stroke- and even in these cases, the jury isn’t out about whether all hope is totally lost- your tissues heal! Bodies are incredibly, amazingly, fantastically resilient. Humans are marvelous and complex, though, and pain can stick around for non-physiological reasons.
Have you ever heard of Pavlov’s dog? Every psychology course talks about this experiment in something called classical conditioning where the experimenter (Pavlov) gives his dog food every time he rings a bell. After a while, the dog will salivate, because it is expecting food, when the bell is rung. Even if food is not present. Let me repeat: this dog, and humans, can learn to expect one response (pain) in the event of a previously unassociated stimulus (movement). If you still have pain in your low back every time you bend over and it’s been going on for more than 6 months, you likely have learned to pair movement and pain. I am not saying that the pain is in your head. It is very real and very valid. But the pain is in your brain. This is not psychological, it’s neurological. If you don’t believe me, watch this incredible video by leading pain science researcher Lorimer Moseley, or this awesome 5 minute video put out by Australia about chronic pain.
There is nothing that you have done wrong, and there is absolutely nothing messed up with you if you are experiencing chronic pain. Pain is your body’s alarm system and it is just trying to protect you. But I want you to know that you aren’t destined to live with it forever. Compelling studies have demonstrated that the more you understand pain, the less you experience it. After all, everything you do, see, feel, and experience is a mere neurological impulse. Think about it: by thinking of food you can make your stomach growl due to physical hunger and by thinking of something that makes you sad, your eyes can start to water. Your thoughts and beliefs undoubtedly have impact on your physical self. We can use this to your advantage!
So, what can be done about it? We need to recondition your brain to find movement to be a rewarding, pleasurable experience instead of a painful one. Starting with gentle aerobic activity and movements that tease, but don’t stress, the nervous system, you can begin to truly heal. Interested in learning more? Seek the guidance of a knowledgeable and compassionate physical therapist near you.